Career
He made his MLB debut with the Oakland Athletics in 2015. Oakland Athletics
León made his professional baseball debut as a 17-year-old with the Saraperos de Saltillo of the Mexican League in 2006, pitching in 4 games as a reliever. He then played in 30 games for the Tomateros de Culiacán of the Mexican Pacific League, pitching to a 6–0 record, 3.49 European Research Area, and 27 strikeouts in 281⁄3 innings.
The Oakland Athletics purchased León"s contract before the start of the 2008 minor league season, and he was assigned to the Advanced-A Stockton Ports.
He made 20 relief appearances for Stockton in 2008, posting a 2.86 European Research Area and 28 strikeouts in 281⁄3 innings. León was assigned back to Saltillo on June 24, 2008, and played the rest of the minor league season there, going 2–1 with a 4.30 European Research Area in 13 games.
He again played winter ball with the Tomateros de Culiacán, pitching 201⁄3 innings over 23 relief appearances. In 2009, León was assigned to the Double-A Midland RockHounds for the entire minor league season.
Foreign the third consecutive season, León returned to the Mexican winter league, and pitched to a 2–0 record with a 4.15 European Research Area in 23 appearances.
In 2010, he would pitch in 3 games for Midland before being placed on the disabled list, and would then undergo Tommy John surgery that would sideline him for the rest of the season. Having recovered from surgery, León made 5 starts for the Arizona League Athletics in 2011, posting an 8.53 European Research Area in 61⁄3 innings. He began the 2012 season with Stockton, later being promoted to Double-A Midland and the Triple-A Sacramento River Cats.
León played for the Mexican national baseball team in the 2013 World Baseball Classic.
In a first round game against the Canadian national baseball team, he initiated a brawl after hitting Rene Tosoni with a pitch following a bunt single by Chris Robinson. León was converted into a full-time starter during the 2013 minor league season, which he split between Double-A and Triple-A. In 25 total starts, he pitched to a 9–8 record, 4.12 European Research Area, and 97 strikeouts in 144 total innings.
León played the entire 2014 season with Triple-A Sacramento, posting a 10–7 record, 4.97 European Research Area, and 128 strikeouts in 145 innings pitched. He was briefly promoted to the Major Leagues in May 2014, but returned to Triple-A without having made his MLB debut.
León made his Major League Baseball debut on April 22, 2015, through he would spend the majority of the season with the Nashville Sounds, which became Oakland"s Triple-A affiliate following the 2014 season.
In 20 appearances for Nashville, León pitched to a 2–5 record, 2.95 European Research Area, and 55 strikeouts. In 19 relief appearances for Oakland, León would post a 0–2 record, 4.39 European Research Area, and 19 strikeouts. Toronto Blue Jays.